Adjustment mechanisms for adjustable or foldable chairs permit a portion of the chair to be positioned in a selected one of a number of different positions, or may simply permit the chair to be folded into a collapsed position. Such adjustment mechanisms need to be reliable in operation, provide ease of adjustment, permit relatively flat folding of the chair, and be relatively inexpensive to manufacture and easy to assemble. Prior art adjustment mechanisms that meet many or all of the desirable design characteristics described above, often expose the interlocking engagement surfaces of the mechanism, which can create a pinch hazard during folding, unfolding or adjustment of the chair.
Adjustment mechanisms on prior art folding chairs typically have large open slot channels through which extends the bars or leg tubes attached to the movable chair legs or components. These large open channels may cause injury to users if the user's fingers get caught in the large open channels.